Codegen Non-Native IR Nodes (#76535)
Add codegen infrastructure to generate IR nodes for non-native ops.
The proposed change is to add a `non_native` key to the `{backend}_native_functions.yaml` file that contains schema definitions similar to what is found in `native_functions.yaml`. e.g.
```
non_native:
...
- func: expand(Tensor input, int[] size, bool is_scalar_expand) -> Tensor
...
```
these definitions are parsed into a `LazyIrSchema` that can be used for generating IR nodes using `GenLazyIR`.
Fixes #74628
CC: @wconstab @desertfire @henrytwo
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76535
Approved by: https://github.com/wconstab
